A light emitting diode is a p-n junction diode having a characteristic in which electric energy is converted into light energy, may be configured with a compound semiconductor of Group III and Group V elements or the like on the periodic table and may represent various colors by adjusting a composition ratio of the compound semiconductor.
In the light emitting diode, when a forward voltage is applied, electrons of an n layer are combined with holes of a p layer, and energy corresponding to an energy gap between a conduction band and a valance band may be generated, and the energy is emitted in the form of light.
A nitride semiconductor is receiving a lot of attention in an optical device and a high-output electronic device development field due to high thermal stability and wide band gap energy thereof. In particular, a blue light emitting diode, a green light emitting diode and an UV light emitting diode using the nitride semiconductor are commercialized and used widely.
The light emitting diode may be classified into a lateral type and a vertical type according to a position of an electrode thereof.
In a conventional vertical type light emitting diode, when a growth substrate is removed and an electrode is connected, an operating voltage VF or an optical loss Po may be affected according to a composition of a semiconductor layer which is in contact with the electrode.